Motor graders are principally designed to be used in road building, however, due to their large size and stability, they have been adapted for other uses such as bank grading, pavements planning, brush cutting and snow blowing.
As one can appreciate, a grader loses power with age, due to wear, and no longer functions at maximum performance. This drop in power is particularly noticeable at lower engine r.p.m. and the operators tend to compensate for this reduction in power by increasing the engine r.p.m.'s and riding the clutch to avoid stalling the engine.
Although older graders may not be as versatile as new machines, they still find spot duty doing many of the lighter jobs such as light roadgrading, snow removal etc. In most cases the loss of power could be overcome by rebuilding the engine, however, this is normally not a feasible solution as other components of the grader have also worn and the reliability of the grader would not justify this investment. A number of accessories such as snow blowers, pavement planners and pavement rippers are available for a grader, however, the grader must be capable of operating at low vehicle ground speed and hence, low r.p.m.'s which is not always possible, as the power output is low at these engine r.p.m.'s causing the engine to stall when the load is applied.
The present invention overcomes this problem by introducing a speed reducer in the power train of the motor grader, such that the grader can operate at these reduced ground speeds while providing the required torque. When these characteristics are not required, the speed reducer may be disengaged returning the drive train to its original status. The device is particularly useful as the normal transmission ratios may be used for light functions and the speed reducer may be engaged when low ground speed, high torque functions are required. For example, the speed reducer would not be used when the grader is travelling to the job site, however, when on site the speed reducer would be engaged allowing the grader to fulfill the desired function.